The present invention relates to a stop motion apparatus for stopping the travel of roving through a roving drafting device of a textile machine.
Typically, roving drafting devices have several related pairs of roving feed rollers with roving fed between the nips defined between each related pair of feed rollers. To stop the travel of roving through the roving drafting device, it is known to provide a stop member for selective insertion into one of the nips between the pair of roving feed rollers to thereby separate the pair of roving feed rollers and press the roving against one of the feed rollers to stop its travel.
To actuate the stop member, the machine typically includes an actuating rod to which the stop member is movably connected. The actuating rod is longitudinally movable to effect insertion and retraction of the stop member from the nip between the pair of roving feed rollers. Typically, the actuating rod is continuously urged by a spring toward its position for effecting insertion of the stop member into the nip. However, the actuating rod is provided with a notch which is engaged by a selectively retractable plunger element and the notch and the selectively retractable plunger element are positioned relative to one another to maintain the actuating rod in its position in which it holds the stop member out of engagement with the nip.
In German Patentsschrift 34 06 397, and electromagnetic assembly is disclosed for controlling the retraction and insertion of a plunger element into a notch of an actuating rod. The electromagnetic assembly is, for example, responsive to a signal transmitted by a yarn monitor which monitors the travel of the roving for interruptions thereat. Once an interruption in the travel of the roving is sensed, the electromagnetic assembly is actuated to retract the plunger element from the actuating rod notch, whereupon the spring engaging the actuating rod automatically moves the actuating rod into the position in which the stop member is inserted into the nip between the roving feed rollers. However, the need exists for improvement in the wear characteristics of the actuating rod and plunger element assemblies described above. Specifically, the relatively frequent insertion and retraction of the plunger element from the notch of the actuating rod eventually tends to cause wear of the surfaces of the notch contacted by the plunger element. As wear of the notch surface increases, the risk that the plunger element will not reliably engage the notch also increases.